Ophthalmic compositions including levodopa, an antioxidant and an aqueous carrier

ABSTRACT

Pharmaceutical ocular compositions include levodopa, an antioxidant and an aqueous carrier. A wide selection of antioxidants can be included in the compositions, such as ascorbic acid, phenolic acids, sorbic acid, sodium bisulfite, sodium metabisulfite, acetyl cysteine, sodium thiosulfate, ethylene diamine tetraacetic acid, sodium nitrite, ascorbyl stearate, ascorbyl palmitate, alpha-thioglycerol, erythorbic acid, cysteine hydrochloride, citric acid, tocopherol or vitamin E, tocopherol acetate, dibutylhydroxytoluene, soybean lecithin, sodium thioglycolate, butylhydroxyanisole, propyl gallate, uric acid, melatonin, and thiourea, as well as salts and combinations of these antioxidants.

This application is a Divisional Application of U.S. application Ser.No. 16/092,291, filed Oct. 9, 2018, which is the U.S. National StageApplication under 35 U.S.C. § 371 of International Application No.PCT/AU2017/050310, filed Apr. 10, 2017, designating the U.S. andpublished in English as WO 2017/177262 A1 on Oct. 19, 2017, which claimspriority to Australian Provisional Application No. 2016901339 entitled“Compositions and Methods of Use” filed on 11 Apr. 2016, the entirecontent of which is hereby incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

This invention relates generally to compositions comprising levodopa andan antioxidant for inhibiting the development or progression of visualdisorders inclusive of visual disorders associated with diabeticretinopathy or Parkinson's disease, and myopia.

BACKGROUND OF THE INVENTION

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that that prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavor to which this specification relates.

Myopia, commonly known as short-sightedness, is a visual disorder causedby excessive elongation (axial length) of the eye during development.Myopia is the leading cause of low vision and the most common eyedisease worldwide, with some estimating that myopia may affect up toone-third of the world's population by the end of the decade. Prevalenceis at its highest in urban East Asia, where in many parts approximately80-90% of school leavers are myopic.

The prevalence of myopia appears to be strongly associated with theamount of time spent outdoors in bright light. Specifically,epidemiological studies have reported that time spent outdoors is apotent protective factor against the development of myopia in children.Animal studies have indicated that this protective effect appears to beassociated with light induced increases in dopamine levels within theeye.

Attempts are being made to reduce the onset and progression of myopia,including increasing the amount of time that children spend outdoors inbright light. However, in many parts of the world geographical locationand local climate restrictions may prevent light levels from beingstrong enough or exposure time from being long enough to protect againstmyopia. Furthermore, social and cultural barriers may prevent increasingthe time children spend outdoors as it is perceived as hinderingeducation and academic progression.

Current treatment options to reduce the progression of myopia includeoptical approaches, such as single vision lenses, multifocal lenses,peripheral lenses and orthokeratology; and pharmaceutical agents, suchas atropine and pirenzepine. With regards to optical approaches,findings from clinical trials have been mixed, with the majority ofoptical approaches showing limited to no long-term effect on the rate ofmyopia progression. Optical approaches are also not targeted atpreventing the onset of myopia, only its progression. Traditionally,treatment with pharmaceutical agents, such as atropine, have been mosteffective at reducing the rate of myopia progression. However, thewidespread use of atropine has been inhibited by concerns aboutpost-treatment rebound effects, as well as the significant short- andlong-term adverse effects.

Accordingly, new therapies for inhibiting the development or progressionof a visual disorder such as myopia are required.

SUMMARY OF THE INVENTION

The present invention is predicated in part on the discovery thataqueous formulations of levodopa in combination with an antioxidant canpenetrate ocular tissues and significantly elevate intraocular dopaminelevels to thereby inhibit the development or progression of a visualdisorder in a subject, particularly a visual disorder involving reduceddopamine levels in the eye, such as a visual disorder associated withdiabetic retinopathy or Parkinson's disease, or myopia.

Levodopa is a naturally occurring precursor to the neurotransmittersdopamine, epinephrine and norepinephrine. Presently, levodopa is orallyadministered for the treatment of Parkinson's disease and elevatesdopamine levels within the central nervous system and, to a lesserextent, systemically. However, oral administration of levodopa is notapplicable to the treatment of visual disorders as it is undesirable tosignificantly elevate dopamine levels within the brain of a subject witha visual disorder and oral administration requires large doses oflevodopa due to systemic distribution.

In one aspect, the present invention provides a pharmaceutical ocularcomposition, comprising, consisting or consisting essentially oflevodopa, an antioxidant and an aqueous carrier. The inventors havefound that it is desirable to formulate levodopa in an aqueous carrierso that it penetrates ocular tissues and is available for elevatingintraocular dopamine levels.

In another aspect of the present invention, there is provided acomposition for inhibiting the development or progression of a visualdisorder, comprising, consisting or consisting essentially of levodopa,an antioxidant and an aqueous carrier. The composition may also be usedfor treating or preventing a visual disorder.

In yet another aspect of the present invention, a method is provided forinhibiting the progression or development of a visual disorder in asubject, comprising administering to the subject the composition of theinvention. In some embodiments, the visual disorder is treated in thesubject. In other embodiments, the visual disorder is prevented in thesubject.

Another aspect of the present invention provides a use of thecomposition of the invention for inhibiting the progression ordevelopment of a visual disorder in a subject.

In a further aspect, the present invention provides a composition of theinvention for use in inhibiting the progression or development of avisual disorder in a subject.

The present invention also provides the use of the composition of theinvention in the manufacture of a medicament for inhibiting theprogression or development of a visual disorder in a subject.

In a still further aspect of the present invention, there is provided amethod of preparing the composition of the invention, comprisingdissolving levodopa in the aqueous carrier at a pH in the range of from0.5 to 2, adding the antioxidant to the composition and adjusting the pHof the composition to a pH in the range of from 5 to 8.

Another aspect of the present invention provides a pharmaceutical ocularcomposition formulated for topical administration to the eye,comprising, consisting or consisting essentially of levodopa, anantioxidant and an aqueous carrier.

In yet another aspect, the present invention provides a topicalcomposition for inhibiting the progression or development of a visualdisorder, comprising, consisting or consisting essentially of levodopa,an antioxidant and an aqueous carrier.

In a further aspect, the present invention provides a method forinhibiting the progression or development of a visual disorder in asubject, comprising administering to the subject a compositioncomprising, consisting or consisting essentially of levodopa, anantioxidant and an aqueous carrier, wherein the visual disorder isselected from a visual disorder associated with diabetic retinopathy, avisual disorder associated with Parkinson's disease, and myopia.

In still a further aspect, there is provided a use of a compositioncomprising, consisting or consisting essentially of levodopa, anantioxidant and an aqueous carrier for inhibiting the progression ordevelopment of a visual disorder in a subject, wherein the visualdisorder is selected from a visual disorder associated with diabeticretinopathy, a visual disorder associated with Parkinson's disease, andmyopia.

In another aspect, the present invention provides a compositioncomprising, consisting or consisting essentially of levodopa, anantioxidant and an aqueous carrier for use in inhibiting the progressionor development of a visual disorder in a subject, wherein the visualdisorder is selected from a visual disorder associated with diabeticretinopathy, a visual disorder associated with Parkinson's disease, andmyopia.

In yet another aspect, there is provided a use of a compositioncomprising, consisting or consisting essentially of levodopa, anantioxidant and an aqueous carrier in the manufacture of a medicamentfor inhibiting the progression or development of a visual disorder in asubject, wherein the visual disorder is selected from a visual disorderassociated with diabetic retinopathy, a visual disorder associated withParkinson's disease, and myopia.

In a further aspect, the invention provides a method for inhibiting theprogression or development of a visual disorder in a subject, comprisingadministering to the subject a composition comprising, consisting orconsisting essentially of levodopa or a pharmaceutically acceptable saltand/or solvate thereof, or prodrug thereof, an antioxidant and anaqueous carrier, wherein the visual disorder is selected from a visualdisorder associated with diabetic retinopathy, a visual disorderassociated with Parkinson's disease, and myopia.

In still a further aspect, there is provided a use of a compositioncomprising, consisting or consisting essentially of levodopa or apharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof, an antioxidant and an aqueous carrier for inhibiting theprogression or development of a visual disorder in a subject, whereinthe visual disorder is selected from a visual disorder associated withdiabetic retinopathy, a visual disorder associated with Parkinson'sdisease, and myopia.

In another aspect, the present invention provides a compositioncomprising, consisting or consisting essentially of levodopa or apharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof, an antioxidant and an aqueous carrier for use in inhibiting theprogression or development of a visual disorder in a subject, whereinthe visual disorder is selected from a visual disorder associated withdiabetic retinopathy, a visual disorder associated with Parkinson'sdisease, and myopia.

In yet another aspect, there is provided a use of a compositioncomprising, consisting or consisting essentially of levodopa or apharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof, an antioxidant and an aqueous carrier in the manufacture of amedicament for inhibiting the progression or development of a visualdisorder in a subject, wherein the visual disorder is selected from avisual disorder associated with diabetic retinopathy, a visual disorderassociated with Parkinson's disease, and myopia.

In particular embodiments, the visual disorder is myopia.

In still another aspect, there is provided a method for inhibiting theprogression or development of a visual disorder in a subject, comprisingadministering to the subject a composition comprising, consisting orconsisting essentially of levodopa or a pharmaceutically acceptable saltand/or solvate thereof, or prodrug thereof, and a pharmaceuticallyacceptable carrier, wherein the visual disorder is selected from avisual disorder associated with diabetic retinopathy, a visual disorderassociated with Parkinson's disease, and myopia.

In a further aspect, there is provided a use of a compositioncomprising, consisting or consisting essentially of levodopa or apharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof, and a pharmaceutically acceptable carrier for inhibiting theprogression or development of a visual disorder in a subject, whereinthe visual disorder is selected from a visual disorder associated withdiabetic retinopathy, a visual disorder associated with Parkinson'sdisease, and myopia.

In another aspect, the present invention provides a compositioncomprising, consisting or consisting essentially of levodopa or apharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof, and a pharmaceutically acceptable carrier for use in inhibitingthe progression or development of a visual disorder in a subject,wherein the visual disorder is selected from a visual disorderassociated with diabetic retinopathy, a visual disorder associated withParkinson's disease, and myopia.

In yet another aspect, there is provided a use of a compositioncomprising, consisting or consisting essentially of levodopa or apharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof, and a pharmaceutically acceptable carrier in the manufacture ofa medicament for inhibiting the progression or development of a visualdisorder in a subject, wherein the visual disorder is selected from avisual disorder associated with diabetic retinopathy, a visual disorderassociated with Parkinson's disease, and myopia.

In some embodiments, the composition comprises, consists or consistsessentially of levodopa and a pharmaceutically acceptable carrier. Inparticular embodiments, the pharmaceutically acceptable carrier is anaqueous carrier.

In particular embodiments, the visual disorder is myopia.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the refractive development in chick eyes in response todiffuser-wear (induction of form deprivation myopia) and treatment withlevodopa/carbidopa compositions.

FIG. 2 shows the changes in axial length in chick eyes in response todiffuser-wear and treatment with levodopa/carbidopa compositions.

FIG. 3 shows the refractive development in chick eyes in response todiffuser-wear and treatment with levodopa or levodopa/carbidopacompositions.

FIG. 4 shows the changes in axial length in chick eyes in response todiffuser-wear and treatment with levodopa or levodopa/carbidopacompositions.

FIG. 5 shows the refractive development in chick eyes in response todiffuser-wear and intravitreal injection of levodopa orlevodopa/carbidopa compositions. *=p<0.05; **=p<0.01; ***=p<0.001relative to G2 (form deprivation myopia only).

FIG. 6 shows the changes in axial length in chick eyes in response todiffuser-wear and intravitreal injection of levodopa orlevodopa/carbidopa compositions. *=p<0.05; **=p<0.01; ***=p<0.001relative to G2 (form deprivation myopia only).

FIG. 7 shows the refractive development in chick eyes in response todiffuser-wear and topical administration of levodopa, levodopa/carbidopaor levodopa/DMSO compositions. *=p<0.05; **=p<0.01; ***=p<0.001 relativeto G13 (form deprivation myopia only).

FIG. 8 shows the changes in axial length in chick eyes in response todiffuser-wear and topical administration of levodopa, levodopa/carbidopaor levodopa/DMSO compositions. *=p<0.05; **=p<0.01; ***=p<0.001 relativeto G13 (form deprivation myopia only).

FIG. 9 shows the refractive development in chick eyes over a period offour weeks in response to diffuser-wear and topical administration oflevodopa [

=age-matched untreated control; ▪=form-deprivation myopia;♦=form-deprivation myopia and topical 0.3% w/v (15 mM) levodopatreatment;

=topical 0.3% w/v (15 mM) levodopa treatment to otherwise untreated eyes(no experimental myopia)].

FIG. 10 shows the changes in axial length in chick eyes over a period offour weeks in response to diffuser-wear and topical administration oflevodopa [

=age-matched untreated control; ζ=form-deprivation myopia;♦=form-deprivation myopia and topical 0.3% w/v (15 mM) levodopatreatment;

=topical 0.3% w/v (15 mM) levodopa treatment to otherwise untreated eyes(no experimental myopia)].

FIG. 11 shows the refractive development in chick eyes in response todiffuser-wear and topical administration of levodopa with ADTN, atropineand pirenzepine. *=p<0.05; **=p<0.01 relative to G2 (form deprivationmyopia only).

FIG. 12 shows the changes in axial length in chick eyes in response todiffuser-wear and topical administration of levodopa with ADTN, atropineand pirenzepine. *=p<0.05; **=p<0.01; ***=p<0.001 relative to G2 (formdeprivation myopia only).

FIG. 13 shows the histological analysis of retinae from chick eyesstained with 1% toluidine blue after diffuser-wear and four weeks oftopical levodopa treatment. FIG. 13A represents stained retinae from thecontralateral control eye of a chick, wherein the other eye is fittedwith a translucent diffuser to induce FDM; FIG. 13B represents stainedretinae from the eye of a chick fitted with a translucent diffuser toinduce FDM; FIG. 13C represents stained retinae from the contralateralcontrol eye of a chick, wherein the other eye is fitted with atranslucent diffuser to induce FDM and is treated with daily topicaladministration of a composition comprising 0.3% w/v levodopa;

FIG. 13D represents stained retinae from the eye of a chick fitted witha translucent diffuser to induce FDM and treated with daily topicaladministration of a composition comprising 0.3% w/v levodopa; FIG. 13Erepresents stained retinae from the contralateral control eye of achick, wherein the other eye is treated with daily topicaladministration of a composition comprising 0.3% w/v levodopa; FIG. 13Frepresents stained retinae from the eye of a chick treated with dailytopical administration of a composition comprising 0.3% w/v levodopa;and FIG. 13G represents stained retinae from the eye of an age-matcheduntreated control chick.

FIG. 14 shows the TUNEL assay analysis of retinae from chick eyes afterdiffuser wear and four weeks of topical levodopa treatment. FIG. 14Arepresents the negative control; FIG. 14B represents the positivecontrol; FIG. 14C represents a retinal section from the eye of anage-matched untreated control chick; FIG. 14D represents a retinalsection from the eye of a chick fitted with a translucent diffuser toinduce FDM; FIG. 14E represents a retinal section from the eye of achick treated with daily topical administration of a compositioncomprising 0.3% w/v levodopa; and FIG. 14F represents a retinal sectionfrom the eye of a chick fitted with a translucent diffuser to induce FDMand treated with daily topical administration of a compositioncomprising 0.3% w/v levodopa.

DETAILED DESCRIPTION OF THE INVENTION I. Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by those of ordinary skillin the art to which the invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, preferred methods andmaterials are described. For the purposes of the present invention, thefollowing terms are defined below.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e. to at least one) of the grammatical object of thearticle. By way of example, “an element” means one element or more thanone element.

By “about” is meant a quantity, level, value, number, frequency,percentage, dimension, size, amount, weight or length that varies by asmuch 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1% to a referencequantity, level, value, number, frequency, percentage, dimension, size,amount, weight or length.

As used herein, the term “and/or” refers to and encompasses any and allpossible combinations of one or more of the associated listed items, aswell as the lack of combinations when interpreted in the alternative(or).

The phrase “aqueous carrier” is used herein to refer to a liquid aqueousdiluent, wherein the aqueous carrier includes, but is not limited to,water, saline, aqueous buffer and aqueous solutions comprising watersoluble or water miscible additives such as glucose or glycerol. Theaqueous carrier may also be in the form of an oil-in-water emulsion.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising”, will be understood to imply the inclusionof a stated integer or step or group of integers or steps but not theexclusion of any other integer or step or group of integers or steps.Thus, the use of the term “comprising” and the like indicates that thelisted integers are required or mandatory, but that other integers areoptional and may or may not be present. By “consisting of” is meantincluding, and limited to, whatever follows the phrase “consisting of”.Thus, the phrase “consisting of” indicates that the listed elements arerequired or mandatory, and that no other elements may be present. By“consisting essentially of” is meant including any elements listed afterthe phrase, and limited to other elements that do not interfere with orcontribute to the activity or action specified in the disclosure for thelisted elements. Thus, the phrase “consisting essentially of” indicatesthat the listed elements are required or mandatory, but that otherelements are optional and may or may not be present depending uponwhether or not they affect the activity or action of the listedelements.

As used herein, the term “condition” refers to an abnormality in thephysical state of the body as a whole or one of its parts.

As used herein, the terms “salts” and “prodrugs” include anypharmaceutically acceptable salt, ester, hydrate, solvate or any othercompound which, upon administration to the recipient, is capable ofproviding (directly or indirectly) a desired compound, or an activemetabolite or residue thereof. Suitable pharmaceutically acceptablesalts include salts of pharmaceutically acceptable inorganic acids suchas hydrochloric, sulfuric, phosphoric, nitric, carbonic, boric, sulfamicand hydrobromic acids, or salts of pharmaceutically acceptable organicacids such as acetic, propionic, butyric, tartaric, maleic,hydroxymaleic, fumaric, citric, lactic, mucic, gluconic, benzoic,succinic, oxalic, phenylacetic, methanesulfonic, toluenesulfonic,benzenesulfonic, salicylic, sulfanilic, aspartic, glutamic, edetic,stearic, palmitic, oleic, lauric, pantothenic, tannic, ascorbic andvaleric acids. Base salts include, but are not limited to, those formedwith pharmaceutically acceptable cations, such as sodium, potassium,lithium, calcium, magnesium, ammonium and alkylammonium. Also, basicnitrogen-containing groups may be quaternized with such agents as loweralkyl halides, such as methyl, ethyl, propyl and butyl chlorides,bromides and iodides; dialkyl sulfates such as dimethyl and diethylsulfate; and others. However, it will be appreciated thatnon-pharmaceutically acceptable salts also fall within the scope of theinvention since these may be useful in the preparation ofpharmaceutically acceptable salts. The preparation of salts and prodrugscan be carried out by methods known in the art. For example, metal saltscan be prepared by reaction of a desired compound with a metalhydroxide. An acid salt can be prepared by reacting an appropriate acidwith a desired compound.

As used herein, the phrase “solubilized form” refers to a form where acompound, such as levodopa, is dissolved in a liquid such that asolution comprising a uniform distribution of the compound is obtainedwhich is substantially free of solid compound. In some embodiments, theliquid is an aqueous carrier as described herein.

The term “subject” as used herein refers to a vertebrate subject,particularly a mammalian or avian subject, for whom therapy orprophylaxis is desired. Suitable subjects include, but are not limitedto, primates; avians; livestock animals such as sheep, cows, horses,deer, donkeys and pigs; laboratory test animals such as rabbits, mice,rats, guinea pigs and hamsters; companion animals such as cats and dogs;and captive wild animals such as foxes, deer and dingoes. In particularembodiments, the subject is a human. In some embodiments, the subject isa human child or young adult, for example, from the age of about 2 yearsto 20 years. However, it will be understood that the aforementionedterms do not imply that symptoms are present.

As used herein, the phrase “visual disorder” refers to a condition thatalters the vision of a subject. In particular embodiments, suchconditions are associated with a decrease in “visual acuity”, which istypically associated with diminishing or lessening of the acuteness orclearness of vision. Thus, a decrease in “visual acuity” typicallyrefers to any measurable diminishing or lessening in the acuteness orclearness of form vision, which is dependent on the sharpness of theretinal focus within the eye and the sensitivity of the interpretativefaculty of the brain. In certain embodiments, visual acuity refers tothe Snellen acuity (e.g. 20/20).

Each embodiment described herein is to be applied mutatis mutandis toeach and every embodiment unless specifically stated otherwise.

2. Compositions

The present invention is based, in part, on the identification thataqueous compositions comprising levodopa and an antioxidant cansignificantly elevate intraocular dopamine levels. Thus, the inventorsconceived that aqueous compositions comprising levodopa and anantioxidant may be useful for inhibiting the development or progressionof a visual disorder involving reduced dopamine levels in the eye.

The amount of levodopa in the composition may depend on the visualdisorder being treated, the characteristics of the subject such asweight and age, and the route of administration. In some embodiments,the levodopa in the composition is in an amount in the range of from0.01% to 60% w/v, 0.02% to 50% w/v, 0.03% w/v to 40% w/v, 0.04% to 30%w/v, 0.05% to 20% w/v, 0.06% to 10% w/v, 0.065% to 9% w/v, 0.07% to 8%w/v, 0.075% to 7% w/v, 0.08% to 6% w/v, 0.085% to 5% w/v, 0.09% to 4%w/v, 0.095% to 3% w/v, 0.1% to 2% w/v or 0.105% to 1% w/v of thecomposition (and all integers therebetween); especially about 0.1%,0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1% w/v of thecomposition.

In preferred embodiments, levodopa is in solubilized form in thecomposition. A skilled person will be well aware of procedures routinelyused in the art to determine the solubility of a compound, for example,the procedures described in Goodwin (2006) Drug Discovery Today:Technologies, 3(1): 67-71; Jouyban (2010) Handbook of Solubility Datafor Pharmaceuticals (CRC Press); or Hefter and Tomkins (2003) TheExperimental Determination of Solubilities (John Wiley & Sons, Ltd). Forexample, the solubility of a compound may be analyzed using UVspectroscopy or high performance liquid chromatography.

In some embodiments, levodopa may be in the form of a derivative such asa pharmaceutically acceptable salt and/or solvate thereof, or prodrugthereof. In some embodiments, levodopa is in the form of a hydrate. Insome embodiments, the pharmaceutically acceptable salt of levodopa isthe hydrochloride salt, such as that described in US 2007/0027216 A1. Insome embodiments the prodrug of levodopa is(2R)-2-phenylcarbonyloxypropyl(2S)-2-amino-3-(3,4-dihydroxyphenyl)propanoatemesylate as described in US 2009/0156679 A1; or a levodopa ester such aslevodopa methyl ester or levodopa ethyl ester, levodopa amide, levodopacarboxamide or levodopa sulfonamide such as those described in US2014/0088192 A1.

Without wishing to be bound by theory, the use of levodopa, which isnaturally synthesized by and present in the human body, is thought toreduce the adverse effects compared with therapy with non-naturallyoccurring pharmaceutical agents and, thus, the compositions of theinvention will be suitable for long-term use. Furthermore, it is thoughtthat the use of a naturally occurring compound will reduce the incidenceof tolerance, which has typically developed with existing pharmaceuticalagents used for the treatment and/or prevention of visual disorders,such as myopia.

The antioxidant may be any compound that slows down, inhibits orprevents the oxidation of any component of the composition of theinvention, especially levodopa. Suitable antioxidants may include, butare not limited to, ascorbic acid or vitamin C, phenolic acids, sorbicacid, sodium bisulfite, sodium metabisulfite, sodium thiosulfate, acetylcysteine, sodium thiosulfate, ethylene diamine tetraacetic acid (EDTA),sodium nitrite, ascorbyl stearate, ascorbyl palmitate,alpha-thioglycerol, erythorbic acid, cysteine hydrochloride, citricacid, tocopherol or vitamin E, tocopherol acetate,dibutylhydroxytoluene, soybean lecithin, sodium thioglycolate,butylhydroxyanisole, propyl gallate, uric acid, melatonin, thiourea, orsalts or combinations thereof. In some embodiments, the antioxidant isascorbic acid or a salt thereof.

The antioxidant may be present in an amount suitable to substantiallyslow down, inhibit or prevent oxidation of any component of thecomposition of the invention, especially levodopa. For example, theantioxidant may be present in an amount in the range of from 0.01% to10% w/v, 0.01% to 5% w/v, 0.03% to 4% w/v, 0.05% to 3% w/v, 0.07% to 2%w/v, 0.09% to 1% w/v or 0.1% to 0.5% w/v of the composition; especiallyin an amount of about 0.1% w/v of the composition.

The aqueous carrier is preferably a pharmaceutically acceptable aqueouscarrier. A variety of pharmaceutically acceptable aqueous carriers wellknown in the art may be used. For example, the aqueous carrier may beselected from, but is not limited to, saline, water, aqueous buffer, anaqueous solution comprising water and a miscible solvent, andcombinations thereof. In some embodiments, the aqueous carrier issaline. When saline is used, it is preferably isotonic for the point ofadministration, such as the eye. For example, in some embodiments thesaline comprises 0.15 to 8% w/v sodium chloride; especially 0.18% to 7%w/v, 0.22% to 5% w/v or 0.45% to 3% w/v sodium chloride; more especially0.5 to 2% w/v or 0.65% to 1.5% w/v sodium chloride; most especiallyabout 0.9% w/v sodium chloride.

In some embodiments where the aqueous carrier is not isotonic, forexample water, the composition may contain a tonicity agent. Anypharmaceutically acceptable tonicity agent well known in the art may beused. Suitable tonicity agents include, but are not limited to, boricacid, sodium acid phosphate buffer, sodium chloride, glucose, trehalose,potassium chloride, calcium chloride, magnesium chloride, polypropyleneglycol, glycerol, mannitol, or salts or combinations thereof. Thetonicity agent may be present in the composition in an amount thatprovides isotonicity with the point of administration, such as the eye,for example in the range of from 0.02 to 15% w/v.

In some embodiments the aqueous carrier is a buffer, wherein the buffermaintains a pH in the range of from 5 to 8, 5.2 to 7.4, 5.5 to 7.4 or5.5 to 6. In some embodiments, the buffer maintains a pH in the range offrom 5.5 to 6.5, especially 5.5 to 6 or 6 to 6.5. Suitable bufferingagents include, but are not limited to, acetic acid, citric acid, sodiummetabisulfite, histidine, sodium bicarbonate, sodium hydroxide, boricacid, borax, alkali metal phosphates, phosphate or citrate buffers, orcombinations thereof. The buffering agent may be present in thecomposition in an amount suitable to maintain the desired pH.

In some embodiments, the pH of the composition is in the range of from 5to 8, 5.2 to 7.4, 5.5 to 7.4 or 5.5 to 6. In some embodiments, the pH ofthe composition is in the range of from 5.5 to 6.5, especially 5.5 to 6or 6 to 6.5. In some embodiments, the pH of the composition is in therange of from 5.5 to 6. In some embodiments, the pH of the compositionis in the range of from 6 to 6.5.

In some embodiments, the composition of the invention further comprisesan inhibitor of aromatic L-amino acid decarboxylase. Suitable inhibitorsof aromatic L-amino acid decarboxylase include, but are not limited to,carbidopa, benserazide, methyldopa, or salts or combinations thereof. Insome embodiments, the inhibitor of aromatic L-amino acid decarboxylaseis carbidopa. Without wishing to be bound by theory, the inhibitor ofaromatic L-amino acid decarboxylase is thought to reduce the conversionof levodopa to dopamine within non-neuronal tissue and, accordingly,increase the bioavailability of levodopa in the composition of theinvention.

The amount of the inhibitor of aromatic L-amino acid decarboxylase inthe composition of the invention will depend on the condition beingtreated, the route of administration of the composition and the amountof levodopa in the composition. The inhibitor of aromatic L-amino aciddecarboxylase should be present in an amount sufficient to substantiallyinhibit the decarboxylation of levodopa. In some embodiments, the ratioof levodopa to the inhibitor of aromatic L-amino acid decarboxylase isin the range of from 20:1 to 1:1, 15:1 to 1:1, 10:1 to 1:1, 9:1 to 1:1,8:1 to 1:1, 7:1 to 1:1, 6:1 to 2:1 or 5:1 to 3:1. In some embodiments,the ratio of levodopa to the inhibitor of aromatic L-amino aciddecarboxylase is about 4:1.

In some embodiments, the inhibitor of aromatic L-amino aciddecarboxylase in the composition is in an amount in the range of from0.0005% to 30% w/v, 0.0025% to 15% w/v, 0.005% to 12.5% w/v, 0.0075% to10% w/v, 0.01% to 7.5% w/v, 0.0125% to 5% w/v, 0.015% to 2.5% w/v,0.0163% to 2.25% w/v, 0.0175% to 2% w/v, 0.0188% to 1.75% w/v, 0.02% to1.5% w/v, 0.0213% to 1.25% w/v, 0.0225% to 1% w/v, 0.0238% to 0.75% w/v,0.025% to 0.5% w/v, 0.0263% to 0.25% w/v of the composition (and allintegers therebetween); especially about 0.025%, 0.03%, 0.035%, 0.04%,0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%,0.09%, 0.095%, 0.1%, 0.125%, 0.15%, 0.175%, 0.2%, 0.225% or 0.25% w/v ofthe composition.

The composition may also comprise or may be administered separately,simultaneously or sequentially with one or more ancillarypharmaceutically active agents. In some embodiments, the ancillarypharmaceutically active agent may increase activation of thedopaminergic system. Exemplary ancillary pharmaceutically active agentsinclude, but are not limited to, a dopamine receptor agonist, agamma-aminobutyric acid (GABA) receptor antagonist and/or a muscarinicacetylcholine receptor antagonist. In some embodiments, thepharmaceutically active agent is an agent that is used for inhibitingthe development or progression of a visual disorder, particularly avisual disorder involving reduced dopamine levels in the eye, such asmyopia.

Without wishing to be bound by theory, it is thought that theadministration of more than one pharmaceutically active agent may reducethe development of tolerance to therapy with one pharmaceutically activeagent alone, particularly when the pharmaceutically active agents havediffering mechanisms of action and/or different molecular targets. Forexample, the administration of the composition of the invention with anexisting pharmaceutical treatment for a visual disorder, such asatropine, may reduce the occurrence of receptor desensitization inresponse to the existing pharmaceutical treatment. It is also thoughtthat the administration of more than one pharmaceutically active agentmay result in a greater therapeutic effect than administration of eachagent alone, such as increased efficacy, decreased adverse effectsand/or decreased tolerance.

In some embodiments, the composition of the invention further comprisesa dopamine receptor agonist. The dopamine receptor agonist may haveagonist activity at any dopamine receptor subtype, including, but notlimited to, any receptor subtype from the D₁-like (D₁ and D₅ receptors)and D₂-like (D₂, D₃ and D₄ receptors) families of receptors, anddopamine receptor heterodimers. Suitable dopamine receptor agonistsinclude, but are not limited to, quinpirole, apomorphine, ropinirole,pramipexole, dexpramipexole, piribedil, rotigotine, bromocriptine,lisuride, cabergoline,2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (ADTN), pergolide,calidopa, dihydrexidine, doxathrine, propylnorapomorphine, quinagolide,roxindole, sumanirole, fenoldopam, ergocornine,1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol (also known asSKF-38393), 2-(N-phenethyl-N-propyl)amino-5-hydroxytetralin (PPHT; alsoknown as N-0434), dihydroergotamine,(1R,3S)-1-(aminomethyl)-3-phenyl-3,4-dihydro-1H-isochromene-5,6-diol(also known as A-68930), carmoxirole, fenoldopam, or salts orcombinations thereof. In some embodiments, the dopamine receptor agonistis dihydroergotamine tartrate,2-(N-phenethyl-N-propyl)amino-5-hydroxytetralin hydrochloride or(1R,3S)-1-(aminomethyl)-3-phenyl-3,4-dihydro-1H-isochromene-5,6-diolhydrochloride. In some embodiments, the dopamine receptor agonist isselected from ADTN, quinpirole, apomorphine, and salts and combinationsthereof; especially ADTN and salts thereof.

The amount of dopamine receptor agonist in the composition may depend onthe condition being treated and the route of administration. In someembodiments, the dopamine receptor agonist in the composition is in anamount in the range of from 0.01% to 20% w/v, 0.01% to 10% w/v, 0.01% to5% w/v, 0.03% to 3% w/v, 0.033% to 2.7% w/v, 0.038% to 2.4% w/v, 0.043%to 2.1% w/v, 0.05% to 1.8% w/v, 0.06% to 1.5% w/v, 0.075% to 1.2% w/v,0.1% to 0.9% w/v or 0.15 to 0.6% w/v of the composition (and allintegers therebetween); especially about 0.2%, 0.21%, 0.22%, 0.23%,0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%,0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.4% w/v of thecomposition.

In some embodiments, the composition of the invention further comprisesa GABA receptor antagonist. The GABA receptor antagonist may haveantagonist activity at any GABA receptor subtype, including, but notlimited to, GABAA, GABAB and/or GABAA-rho (formerly GABAc) receptors.Suitable GABA receptor antagonists include, but are not limited to,bicuculline, flumazenil, gabazine, phenylenetetrazol,(1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA),(3-aminopropyl)(cyclohexylmethyl)phosphinic acid (also known asCGP-46381), 4-imidazoleacetic acid, picrotoxin, piperidin-4-ylphosphinicacid (PPA), piperidin-4-ylseleninic acid (SEPI),3-aminopropyl-N-butylphosphinic acid (also known as CGP-36742),(piperidin-4-yl)methylphosphinic acid (P4MPA), or salts or combinationsthereof.

In some embodiments, the GABA receptor antagonist is selected fromTPMPA, bicuculline and salts and combinations thereof.

The amount of GABA receptor antagonist in the composition may depend onthe condition being treated and the route of administration. In someembodiments, the GABA receptor antagonist in the composition is in anamount in the range of from 0.01% to 20% w/v, 0.01% to 10% w/v, 0.01% to5% w/v, 0.03% to 3% w/v, 0.033% to 2.7% w/v, 0.038% to 2.4% w/v, 0.043%to 2.1% w/v, 0.05% to 1.8% w/v, 0.06% to 1.5% w/v, 0.075% to 1.2% w/v,0.1% to 0.9% w/v or 0.15 to 0.6% w/v of the composition (and allintegers therebetween); especially about 0.2%, 0.21%, 0.22%, 0.23%,0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%,0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.4% w/v of thecomposition.

In some embodiments, the composition of the invention further comprisesa muscarinic acetylcholine receptor antagonist. The muscarinicacetylcholine receptor antagonist may have antagonist activity at anymuscarinic acetylcholine receptor subtype, including, but not limitedto, M₁, M₂, M₃, M₄ and M₅ receptors. Suitable muscarinic receptorantagonists include, but are not limited to, atropine, pirenzepine,himbacine, hyoscine, cyclopentolate, ipratropium, oxitropium,tropicamide, oxybutynin, tolterodine, diphenhydramine, dicycloverine,flavoxate, tiotropium, trihexyphenidyl, solifenacin, darifenacin,benzatropine, mebeverine, procyclidine, aclidinium, muscarinic toxin 1(MT1), muscarinic toxin 2 (MT2), muscarinic toxin 3 (MT3), muscarinictoxin 4 (MT4), muscarinic toxin 7 (MT7), or salts or combinationsthereof. In some embodiments, the muscarinic acetylcholine receptorantagonist is selected from atropine, pirenzepine, himbacine, and saltsand combinations thereof; especially atropine and pirenzepine and saltsand combinations thereof.

The amount of muscarinic acetylcholine receptor antagonist in thecomposition may depend on the condition being treated and the route ofadministration. In some embodiments, the muscarinic acetylcholinereceptor antagonist in the composition is in an amount in the range offrom 0.01% to 30% w/v, 0.2% to 20% w/v, 0.22% to 18% w/v, 0.25% to 16%w/v, 0.29% to 14% w/v, 0.33% to 12% w/v, 0.4% to 10% w/v, 0.5% to 8%w/v, 0.67% to 6% w/v or 1% to 4% w/v of the composition (and allintegers therebetween); especially about 0.1%, 0.2%, 0.3%, 0.4%, 0.5%,0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%,1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%,3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4% w/v ofthe composition. In particular embodiments, the muscarinic acetylcholinereceptor antagonist in the composition is in an amount in the range offrom 0.0001% to 30% w/v, 0.0003% to 20% w/v, 0.0005% to 10% w/v, 0.0007%to 5% w/v, 0.0009% to 2% w/v, 0.001% to 1% w/v, 0.003% to 0.5%, 0.005%to 0.2%, 0.007% to 0.15% w/v, or 0.009% to 0.1% of the composition (andall integers therebetween); especially about 0.001%, 0.002%, 0.003%,0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.011%, 0.012%,0.013%, 0.014%, 0.015%, 0.016%, 0.017%, 0.018%, 0.019% or 0.02% w/v ofthe composition; most especially about 0.01% w/v of the composition.

The composition of the invention may further comprise a surfactant. Avariety of pharmaceutically acceptable surfactants well known in the artmay be used. Exemplary surfactants include, but are not limited to,surfactants of the following classes: alcohols; amine oxides; blockpolymers; carboxylated alcohol or alkylphenol ethoxylates; carboxylicacids/fatty acids; ethoxylated arylphenols; ethoxylated fatty esters,oils, fatty amines or fatty alcohols such as cetyl alcohol; fattyesters; fatty acid methyl ester ethoxylates; glycerol esters such asglycerol monostearate; glycol esters; lanolin-based derivatives;lecithin or derivatives thereof; lignin or derivatives thereof; methylesters; monoglycerides or derivatives thereof; polyethylene glycols;polypropylene glycols; alkylphenol polyethylene glycols; alkyl mercaptanpolyethylene glycols; polypropylene glycol ethoxylates; polyethyleneglycol ethers such as Cetomacrogol 1000; polymeric surfactants;propoxylated and/or ethoxylated fatty acids, alcohols or alkylphenols;protein-based surfactants; sarcosine derivatives; sorbitan derivativessuch as polysorbates; sorbitol esters; esters of sorbitol polyglycolethers; fatty acid alkylolamides; N-alkylpolyhydroxy fatty acid amide;N-alkoxypolyhydroxy fatty acid amide; alkyl polyglycosides; quaternaryammonium compounds such as benzalkonium chloride; cyclodextrins such asalpha-, beta- or gamma-cyclodextrin; sucrose or glucose esters orderivatives thereof; sulfosuccinates such as dioctyl sodiumsulfosuccinate; or combinations thereof. Without wishing to be bound bytheory, the presence of a surfactant may be useful in emulsifying theaqueous carrier with an oil if an oil is included in the composition andmay enhance the penetration of the active ingredients, such as levodopa,through the corneal epithelium. The surfactant may be present in anamount in the range of from about 0.1% to 30% w/v of the composition.

In some embodiments, the composition of the invention further comprisesa rheology modifier. The rheology modifier may be used to alter thesurface tension and flow of the composition and may also contribute tothe composition's residence time on the surface of the eye whenformulated for topical administration. Suitable rheology modifiers arewell known in the art. For example, the rheology modifier may beselected from, but is not limited to, hyaluronic acid, chitosan,polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, dextran,methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose,hydroxypropylcellulose, hydroxypropyl guar, acrylates such as Carbopolpolymers, poloxamers, gum arabic, xanthan gum, guar gum, locust beangum, carboxymethylcellulose, alginate, starch (from rice, corn, potatoor wheat), carrageenan, konjac, aloe vera gel, agarose, pectin,tragacanth, curdlan gum, gellan gum, scleroglucan, and derivatives andcombinations thereof. The rheology modifier should be present in anamount sufficient to obtain the desired viscosity of the composition.The rheology modifier may be present in an amount in the range of fromabout 0.5% to 5% w/v of the composition.

The composition of the invention may further comprise a preservative.The preservative may be particularly useful for preventing microbialcontamination in a composition which is subject to multiple uses fromthe same container, for example, if the composition of the invention isformulated for topical administration in a multiple unit dose form.Suitable preservatives include any pharmaceutically acceptablepreservative routinely used in the art to prevent microbialcontamination in a composition. Non-limiting examples include sodiumperborate, stabilized oxychloro complex, polyquaternium-1,phenylmercuric acid, benzalkonium chloride, chlorbutanol, phenylmercuricacetate, phenylmercuric nitrate, chlorhexidine, benzododecinium bromide,cetrimonium chloride, thiomersal, methyl parahydroxybenzoate, propylparahydroxybenzoate, polyquaternium ammonium chloride, polyaminopropylbiguanide, hydrogen peroxide, benzoic acid, phenolic acids, sorbic acid,benzyl alcohol or salts or combinations thereof. The preservative shouldbe present in an amount that provides adequate preservative activity.For example, the preservative may be present in an amount in the rangeof from about 0.001% to 1% w/v of the composition.

It may be desirable to increase the permeation of the composition intothe eye. This may be particularly useful when the composition isformulated for topical administration. Accordingly, the composition ofthe invention may also comprise a permeation enhancing agent. In thisregard, the composition of the invention may comprise, but is notlimited to, dimethyl sulfoxide (DMSO); cyclodextrins such as alpha-,beta- or gamma-cyclodextrin; EDTA; decamethonium; glycocholate; cholate;saponins; fusidate; taurocholates; polyethylene glycol ethers;polysorbates; or salts, derivatives or combinations thereof. In someembodiments, the permeation enhancing agent is dimethyl sulfoxide. Otherpermeation enhancing agents include nanoparticles, liposomes or micelleswhich, in some embodiments, encapsulate levodopa. The permeationenhancing agent should be present in an amount that facilitatespermeation of levodopa across the corneal epithelium. For example, thepermeation enhancing agent may be present in an amount in the range offrom about 0.1% to 30% w/v of the composition.

In particular embodiments, the permeation enhancing agent is a micelle.Suitable micelles include, but are not limited to, a Triton X-100micelle e.g. the micelle described in Jodko-Piorecka and Litwinienko(2015) Free Radical Biology and Medicine, 83: 1-11; a surfactantnanomicelle e.g. a nanomicelle formed with sodium dodecyl sulfate,dodecyltrimethylammonium bromide, n-dodecyl tetra (ethylene oxide),Vitamin E TGPS, octoxynol-40 and/or dioctanoyl phosphatidylcholine; apolymeric micelle e.g. a micelle formed with poly(caprolactone), poly(D,L-lactide), polypropylene oxide, poly(β-benzyl-1-aspartate), methoxypoly(ethylene glycol)-hexylsubstituted poly(lactide), Pluronic F127poly(oxyethylene)/poly(oxypropylene)/poly(oxyethylene), F 68, F 127,poly(hydroxyethylaspartamide)-polyethylene glycol-hexadecylamine,polyoxyl 40 stearate, N-isopropylacrylamide with vinyl pyrrolidone andacrylic acid cross-linked with N,N′-methylene bis-acrylamide, PluronicF127 and chitosan, poly(lactic acid), poly(glycolic acid), poly(ethyleneglycol), poly(ethylene oxide), N-phthaloylcarboxymethylchitosan,poly(2-ethylhexyl acrylate)-b-poly(acrylic acid), poly(tert-butylacrylate)-b-poly(2-vinylpyridine), poly(ethyleneoxide)-b-polycaprolactone, poly(ε-caprolactone)-b-poly(ethyleneglycol)-b-poly(ε-caprolactone), poly(ε-caprolactone)-b-poly(methacrylicacid),poly(ethyleneglycol)-b-poly(ε-caprolactone-co-trimethylenecarbonate),poly(aspartic acid)-b-polylactide, poly(ethyleneglycol)-block-poly(aspartate-hydrazide),poly(N-isopropylacrylamide-co-methacrylic acid)-g-poly(D,L-lactide)and/or stearic acid-grafted chitosan oligosaccharide; or the micellesdisclosed in US 2009/0092665 A1. In particular embodiments, the micelleencapsulates the levodopa in the composition.

The composition of the invention may also further comprise a chelatingagent. Suitable chelating agents include, but are not limited to, aminocarboxylic acids or salts thereof such as EDTA, nitrilotriacetic acid,nitrilotripropionic acid, diethylenetriamine pentacetic acid,2-hydroxyethyl-ethylenediamine-triacetic acid,1,6-diamino-hexamethylene-tetraacetic acid, 1,2-diamino-cyclohexanetetraacetic acid, 0,0′-bis(2-aminoethyl)-ethyleneglycol-tetraaceticacid, 1,3-diaminopropane-tetraacetic acid,N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid,ethylenediamine-N,N′-diacetic acid, ethylenediamine-N,N′-dipropionicacid, triethylenetetraamine hexaacetic acid,7,19,30-trioxa-1,4,10,13,16,22,27,33-octaazabicyclo[11,11,11]pentatriacontane(O-bis-tren), ethylenediamine-N,N′-bis(methylenephosphonic acid),iminodiacetic acid, N,N-bis(2-hydroxyethyl)glycine (DHEG),1,3-diamino-2-hydroxypropane-tetraacetic acid,1,2-diaminopropane-tetraacetic acid,ethylenediamine-tetrakis(methylenephosphonic acid),N-(2-hydroxyethyl)iminodiacetic acid, or combinations or salts thereof;especially pharmaceutically acceptable salts or mixed salts of EDTA,such as disodium, trisodium, tetrasodium, dipotassium, tripotassium,lithium, dilithium, ammonium, diammonium, calcium or calcium-disodium;most especially disodium EDTA. The chelating agent may be present in anamount in the range of from about 0.01% to 1% w/v of the composition.

In some embodiments, the composition of the invention may furthercomprise an oil. Suitable oils include, but are not limited to, almondoil; castor oil; mineral oil; olive oil; peanut oil; coconut oil;soybean oil; corn oil; anise oil; clove oil; cassia oil; cinnamon oil;arachis oil; maize oil; caraway oil; rosemary oil; peppermint oil;eucalyptus oil; seed oils such as canola oil, cottonseed oil, linseedoil, safflower oil, sesame oil or sunflower oil; silicone oil; orcombinations thereof. Such oils may be included in the composition inthe form of an oil-in-water emulsion, optionally with a surfactant, withthe aqueous carrier. The oil may be present in an amount in the range offrom about 0.1% to 20% w/v of the composition.

The composition of the invention may further comprise any otherpharmaceutically acceptable excipient commonly present in ocularformulations. For example, the compositions may further comprise analcohol such as isopropanol, benzyl alcohol, cetearyl alcohol orethanol; a lubricant such as glucose, glycerol, polyethylene glycol,polypropylene glycol or derivatives thereof; a polysaccharide such aschitosan, chitin, dermatan, hyaluronate, heparin, dermatan, chondroitin,cyclodextrin or derivatives thereof; or combinations thereof. Suitablepharmaceutically acceptable carriers include, but are not limited to,aqueous carriers as described herein, oils as described herein, fattyacids, a silicone liquid carrier such as a perfluorocarbon orfluorinated liquid carrier, for example, as described in U.S. Pat. No.6,458,376 B1, and combinations thereof. In some embodiments, thecomposition does not comprise an antioxidant.

In particular embodiments, the composition of the invention may beformulated for topical administration to the eye. In this regard, thecomposition of the invention may be in the form of an eye drop or gel;especially an eye drop. Without wishing to be bound by theory,formulating the composition for topical administration to the eye isthought to increase user compliance, particularly when the compositionis used as a preventative or control measure. This may be particularlyimportant if the composition is administered to a child subject.Furthermore, such a formulation may reduce the incidence of off targeteffects of levodopa.

In some embodiments, the composition of the invention is formulated forpenetration of levodopa through the corneal epithelium. In preferredembodiments, greater than about 10%, 20%, 30%, 40%, 50%, 60%, 70% or 80%of the dose of levodopa penetrates the corneal epithelium.

When formulated as an eye drop or gel, the composition of the inventionmay be in a single unit dose or multiple unit dose form, preferably amultiple unit dose form.

In alternative embodiments, the composition of the invention isformulated for direct injection into the eye. In particular embodiments,the composition of the invention is formulated for intravitreal,subconjunctival, intracameral, intrascleral, intracorneal or subretinalinjection; especially intravitreal, intrascleral or intracornealinjection. In some embodiments, the composition of the invention isformulated for suprachoroidal injection. In some embodiments, thecomposition of the invention is formulated for injection via amicroneedle, for example, via intrascleral or intracornealadministration.

Other excipients and components of the composition may be readilydetermined by a person skilled in the art. Techniques for formulationand administration may be found in, for example, Remington (1980)Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, Pa.,latest edition; and suitable excipients may be found in, for example,Katdare and Chaubel (2006) Excipient Development for Pharmaceutical,Biotechnology and Drug Delivery Systems (CRC Press).

A person skilled in the art would be familiar with the components of thecompositions of the invention and, accordingly, would readily be able tosynthesize or source the components, such as from, for example, SigmaAldrich Co. LLC. For example, levodopa is commercially available from anumber of sources, such as Sigma-Aldrich Co. LLC, and a synthetic routeis available in, for example, Vandanyan and Hruby (2006) Synthesis ofEssential Drugs (Elsevier) pages 136-137; Vandanyan and Hruby (2016)Synthesis of Best-Seller Drugs (Academic Press) pages 180-182; and U.S.Pat. No. 4,962,223; all of which are incorporated herein by reference intheir entirety.

3. Processes for Preparing the Composition

The inventors have found that the composition of the invention may beprepared by dissolving levodopa in the aqueous carrier at a pH in therange of from 0.5 to 2.5, adding the antioxidant to the composition andadjusting the pH of the composition to a pH in the range of from 5 to 8.

The pH at which levodopa is dissolved in the aqueous carrier is in therange of from 0.5 to 2.5, preferably 1 to 2, most especially 1.5 to 2.In some embodiments, levodopa is dissolved in the aqueous carrier at apH of about 2. Without wishing to be bound by theory, the maintenance ofthe aqueous carrier at an acidic pH is thought to increase thesolubility of levodopa in the aqueous carrier.

The pH of the final composition is in the range of from 5 to 8,preferably 5.5 to 7.5, especially 5.5 to 7.4, most especially 5.5 to 6.In some embodiments, the pH of the composition is in the range of from5.5 to 6.5, especially 5.5 to 6 or 6 to 6.5. In some embodiments, the pHof the composition is adjusted to a pH in the range of from 5.5 to 6. Insome embodiments, the pH of the composition is adjusted to a pH in therange of from 6 to 6.5.

The pH of the compositions may be adjusted using any pharmaceuticallyacceptable pH adjusting agent that is routinely used in the art, such ashydrochloric acid, sodium hydroxide, etc. A person skilled in the artwill be well aware of suitable agents.

The inhibitor of aromatic L-amino acid decarboxylase, excipients andother components of the composition of the invention may be added to thecomposition at any stage of the process. For example, the inhibitor ofaromatic L-amino acid decarboxylase may be added to the solution oflevodopa and aqueous carrier at a pH in the range of from 0.5 to 2.5prior to adjusting the pH of the composition to a pH in the range offrom 5 to 8, or may be added to the composition after adjusting the pHof the composition to a pH in the range of from 5 to 8. In someembodiments, the inhibitor of aromatic L-amino acid decarboxylase andlevodopa are simultaneously dissolved in the aqueous carrier at a pH inthe range of from 0.5 to 2.5.

The composition of the invention may also be sterilized prior to use,for example by filtration, autoclaving and/or gamma irradiation.

Without wishing to be bound by theory, the preparation of thecomposition of the invention using this process increases the solubilityof levodopa in the aqueous carrier, thereby removing the need for thepresence of organic carriers or agents which enhance the solubility oflevodopa in the composition.

4. Methods of Prevention and Treatment of a Visual Disorder

The compositions of the invention are useful for inhibiting theprogression or development of a visual disorder in a subject,particularly a visual disorder involving reduced dopamine levels in theeye, such as a visual disorder associated with diabetic retinopathy orParkinson's disease, or myopia. Accordingly, the compositions of theinvention may be used in methods of inhibiting the progression ordevelopment of a visual disorder in a subject. The compositions of theinvention may also be used in the manufacture of a medicament for theuses described herein.

The compositions of the invention are useful for inhibiting theprogression of a visual disorder in a subject. In this regard, thecompositions of the invention may be used for treating a visualdisorder. In some embodiments, the compositions of the invention mayslow the progression of a visual disorder in a subject.

The compositions of the invention are also useful for inhibiting thedevelopment of a visual disorder in a subject. Thus, the compositions ofthe invention are useful for preventing a visual disorder in a subject.In some embodiments, the compositions of the invention may delay theonset of a visual disorder in a subject, i.e. may increase the age ofthe subject at which the visual disorder is developed and, therefore,the possible severity of the visual disorder.

The visual disorder may be any visual disorder involving reduceddopamine levels in the eye, particularly reduced dopamine levels in theretina. Accordingly, the visual disorder may be any visual disorderwhere increasing dopamine levels in the eye, particularly the retina, isassociated with effective inhibition of the progression or developmentof the visual disorder.

There are numerous visual disorders involving reduced dopamine levels inthe eye. For example, the visual disorder may be, but is not limited to,a visual disorder associated with diabetic retinopathy or Parkinson'sdisease, myopia, increased ocular growth, reduced spatial and temporalcontrast sensitivity, amblyopia, blurred or double vision, eye strain,trouble with voluntarily opening the eyes (apraxia), eyelid spasms(blepharospasm), excessive blinking, altered color perception, reduceddepth perception or visual hallucinations. In some embodiments, thevisual disorder is selected from a visual disorder associated withdiabetic retinopathy or Parkinson's disease, and myopia. In particularembodiments, the visual disorder is myopia.

In some embodiments, the visual disorder is not associated withParkinson's disease.

The method includes administering the composition of the invention to asubject. The composition of the invention may be administered locallythrough topical administration to the surface of the eye or via directinjection into the eye.

In some embodiments, the composition is topically administered to theeye, for example, in the form of an eye drop or gel. In preferredembodiments, the composition is applied as an eye drop. The compositionof the invention may be applied to any surface of the eye, preferablythe cornea/sclera, thereby allowing the components present in thecomposition, particularly levodopa, to penetrate into the eye. In someembodiments, the composition is formulated such that levodopa penetratesthrough the corneal epithelium.

In other embodiments, the composition is administered by injection intothe eye. For example, the composition may be injected directly into thesclera, anterior chamber or vitreous, or may be injected into thesubconjunctival, peribulbar, retrobulbar or suprachoroidal space. Inparticular embodiments, the composition of the invention is administeredvia intravitreal, subconjunctival, intracameral, intrascleral,intracorneal or subretinal injection; especially intravitreal,intrascleral or intracorneal injection. In some embodiments, thecomposition of the invention is administered via suprachoroidalinjection. In some embodiments, the composition of the invention isadministered by intravitreal injection. In other embodiments, thecomposition of the invention is injected using a microneedle, forexample, via intrascleral or intracorneal administration. Foradministration via these routes, the composition of the invention may bein the form of a sterile injectable solution.

The portion of the eye into or onto which the composition of theinvention is preferably administered is the portion that allows forpenetration of the components, particularly levodopa, into the eye,preferably into the retina. Administration is preferably performed onthe cornea/sclera and conjunctiva for topical administration, or thecomposition may be injected into the subconjunctival, peribulbar,retrobulbar or suprachoroidal space, or into the sclera, cornea,anterior chamber or vitreous.

When applied topically, the composition of the invention may be usedwith both hard and soft contact lenses.

Dosage regimens may be established for different indications inaccordance with methodologies well known to a person skilled in the art.The dosage of the composition will depend on the condition to betreated, the age of the subject and the route of administration.

The composition of the invention may be administered topically or byinjection in a suitable amount so as to provide a dose of levodopa inthe range of from 0.001 mg/kg/day to 12 mg/kg/day, especially from 0.001mg/kg/day to 4 mg/kg/day, more especially from 0.001 mg/kg/day to 2mg/kg/day. In some embodiments the composition is administered in asuitable amount so as to provide a dose of levodopa in the range of from0.001 mg/kg/day to 30 mg/kg/day, especially from 0.001 mg/kg/day to 12mg/kg/day, more especially from 0.001 mg/kg/day to 4 mg/kg/day, mostespecially from 0.001 mg/kg/day to 2 mg/kg/day

When administered topically as an eye drop, the composition of theinvention may be administered in an amount in the range of from 1 to 6drops per eye (and all integers therebetween), which may equate to, forexample, an amount in the range of from about 0.04 mL to 0.24 mL per eye(and all integers therebetween). Drops may be applied to each eye from 1to 4 times daily. When the composition of the invention is formulated asa gel, an equivalent dose is provided. A skilled person will be aware ofsuitable dispensers for topical application of the composition of theinvention.

When administered by injection, the composition of the invention may beadministered in an amount in the range of from 0.001 mL to 0.5 mL (andall integers therebetween), especially about 0.01 mL. The composition ofthe invention may be administered at a frequency of once per week toonce daily.

In order that the invention may be readily understood and put intopractical effect, particular preferred embodiments will now be describedby way of the following non-limiting examples.

EXAMPLES

All materials used in the following examples are commercially availablefrom, for example, Sigma-Aldrich Co. LLC unless otherwise indicated.

Example 1—Method of Producing 0.3% W/V Levodopa Composition

12 mg levodopa (commercially available from Sigma-Aldrich Co. LLC) wasdissolved in a solution containing 0.15 M hydrochloric acid, 0.1%ascorbic acid and 1× phosphate buffered saline (PBS) (solution isapproximately pH 2). Once levodopa was dissolved, the solution wasadjusted to a pH of 6 using sodium hydroxide to obtain a final volume of4 mL.

Example 2—Method of Producing 0.3% W/V Levodopa, 0.08% W/V CarbidopaComposition

12 mg levodopa was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS (solution isapproximately pH 2). Once levodopa was dissolved, 3 mg of carbidopa(commercially available from Sigma-Aldrich Co. LLC) was added to thesolution. The solution was adjusted to a pH of 6 using sodium hydroxideto obtain a final volume of 4 mL.

Example 3—Method of Producing 0.03% W/V Levodopa, 0.008% W/V CarbidopaComposition

1.2 mg levodopa was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS (solution isapproximately pH 2). Once levodopa was dissolved, 0.3 mg of carbidopawas added to the solution. The solution was adjusted to a pH of 6 usingsodium hydroxide to obtain a final volume of 4 mL.

Example 4—Efficacy of Levodopa Compositions in Preventing FormDeprivation Myopia

44 male White Cockerel chickens were randomly assigned to one of 11treatment groups as defined below (n=4 per group) and were treated for afive day period. G1-G11 represent the labelling system used in FIGS. 1and 2.

G1. Age-matched untreated control groupG2. Chicks fitted with a translucent diffuser over their left eye toinduce form-deprivation myopia (FDM)G3. Chicks fitted with a translucent diffuser over their left eye anddaily intravitreal injection of the composition of Example 2G4. Chicks fitted with a translucent diffuser over their left eye anddaily topical administration of the composition of Example 2G5. Chicks fitted with a translucent diffuser over their left eye anddaily oral administration of 10 mg/kg levodopa, 2.5 mg/kg carbidopa as apowderG6. Chicks fitted with a translucent diffuser over their left eye anddaily intravitreal injection of the composition of Example 3G7. Chicks fitted with a translucent diffuser over their left eye anddaily topical administration of the composition of Example 3G8. Chicks fitted with a translucent diffuser over their left eye anddaily intravitreal injection of a vehicle solution (buffered 0.1%ascorbic acid in 1×PBS)G9. Chicks fitted with a translucent diffuser over their left eye anddaily topical administration of a vehicle solution (buffered 0.1%ascorbic acid in 1×PBS)G10. Daily intravitreal injection of the composition of Example 2G11. Daily topical administration of the composition of Example 2

For the drug treatments, the compositions were administered under lightisoflurane anesthesia using intravitreal injection or topicaladministration.

Intravitreal injection was performed as follows: Using a 30 gauge needleattached to a Hamilton syringe, 10 μL (0.01 mL) of the test compositionwas injected into the vitreous chamber of the eye once daily.

Topical administration was performed as follows: Two drops of 40 μL (twodrops of 0.04 mL, or 0.08 mL total) of the test composition was appliedto the corneal surface of the eye using an eye drop dispenser. Dropswere applied to the chicks twice daily.

To determine changes in the rate of eye growth and the development ofmyopia, changes in axial length and refraction were assessed. Myopia isassociated with excessive elongation of the eye in the axial directionrelative to normal growth rates. Such excessive axial elongation leadsto a relative myopic change in refraction. Axial length and refractionwere measured using A-scan ultrasonography (Biometer AL-100; TomeyCorporation, Nagoya, Japan) and automated infrared photo-retinoscopyrespectively. Statistical analysis of changes in both refraction andaxial length between groups involved a one-way ANOVA test followed by aStudent's T-test with Bonferroni correction. All data are presented asthe mean±the standard deviation of the mean (SEM).

Results

The results are presented in FIGS. 1 and 2. Attachment of a translucentdiffuser over the left eye induced a significant myopic shift inrefraction over a five day period (G2, FIG. 1) associated with excessiveaxial elongation (G2, FIG. 2), relative to that seen in contralateralcontrol eyes (G2, FIGS. 1 and 2; refraction, p<0.001; axial lengthp<0.001) or age-matched untreated control eyes (G1, FIGS. 1 and 2;refraction, p<0.001; axial length p<0.001). There was no difference inthe refractive development or axial length between contralateral controleyes of different treatment groups relative to each other (refractionp=0.34; axial length p=0.39) or age-matched untreated eyes (refractionp=0.54; axial length p=0.42).

Daily administration of levodopa/carbidopa compositions, through eitherintravitreal injection or topical administration, abolished thedevelopment of form-deprivation myopia over a five day period (G3, G4,G6 and G7, FIGS. 1 and 2). Specifically, the axial length ofdiffuser-treated eyes that were administered levodopa/carbidopacompositions daily via intravitreal injection or topical application(G3, G4, G6 and G7, FIG. 2), were not different to that seen in eithercontralateral control eyes (injection levodopa/carbidopa composition ofExample 2, p=0.38; injection levodopa/carbidopa composition of Example3, p=0.22; drops levodopa/carbidopa composition of Example 2, p=0.33;drops levodopa/carbidopa composition of Example 3, p=0.24) orage-matched untreated control eyes (injection levodopa/carbidopacomposition of Example 2, p=0.27; injection levodopa/carbidopacomposition of Example 3, p=0.18; drops levodopa/carbidopa compositionof Example 2, p=0.26; drops levodopa/carbidopa composition of Example 3,p=0.19). Similarly, there was no significant difference in refractivedevelopment between eyes treated with diffusers plus levodopa/carbidopacompositions (G3, G4, G6 and G7, FIG. 1) relative to eithercontralateral control (injection levodopa/carbidopa composition ofExample 2, p=0.26; injection levodopa/carbidopa composition of Example3, p=0.19; drops levodopa/carbidopa composition of Example 2, p=0.23;drops levodopa/carbidopa composition of Example 3, p=0.16) orage-matched untreated eyes (injection levodopa/carbidopa composition ofExample 2, p=0.19; injection levodopa/carbidopa composition of Example3, p=0.16; drops levodopa/carbidopa composition of Example 2, p=0.16;drops levodopa/carbidopa composition of Example 3, p=0.15). Therefore,eyes treated with compositions comprising levodopa and carbidopa showedneither increased axial elongation, nor a myopic shift in refraction inresponse to diffuser-wear.

Daily oral administration of levodopa and carbidopa for five days (G5,FIGS. 1 and 2) at an amount equivalent to that provided by topicalapplication (10 mg/kg/day of levodopa and 2.5 mg/kg/day of carbidopa),reduced the development of FDM by roughly 50% relative to that seen inthe FDM only group (G2) (axial length, p<0.05; refraction, p<0.05). Thisprotection is significantly less than that seen in response to eitherintravitreal injection or topical administration of levodopa/carbidopacompositions, indicating that direct application to the eye is a moreeffective route of administration.

Injection or topical administration of the vehicle solution todiffuser-treated eyes for a five day period did not alter thedevelopment of FDM (G8 and G9, FIGS. 1 and 2). Furthermore, injection ortopical application of levodopa/carbidopa compositions to otherwiseuntreated eyes (G10 and G11, FIGS. 1 and 2), did not alter axial growth(injection, p=0.63; drops, p=0.57) or refractive development (injection,p=0.71; drops, p=0.62), relative to that seen in age-matched untreatedcontrol eyes.

Example 5—Efficacy of Levodopa Compositions in Preventing FormDeprivation Myopia

32 male White Cockerel chickens were randomly assigned to one of 8treatment groups (n=4 per group) as defined below and were treated for afive day period. G1-G8 represent the labelling system used in FIGS. 3and 4.

G1. Age-matched untreated control groupG2. Chicks fitted with a translucent diffuser over their left eye toinduce FDMG3. Chicks fitted with a translucent diffuser over their left eye anddaily intravitreal injection of the composition of Example 2G4. Chicks fitted with a translucent diffuser over their left eye anddaily intravitreal injection of the composition of Example 1G5. Chicks fitted with a translucent diffuser over their left eye anddaily topical administration of the composition of Example 2G6. Chicks fitted with a translucent diffuser over their left eye anddaily topical administration of the composition of Example 1G7. Chicks fitted with a translucent diffuser over their left eye anddaily oral administration of 10 mg/kg levodopa, 2.5 mg/kg carbidopa as apowderG8. Chicks fitted with a translucent diffuser over their left eye anddaily oral administration of 10 mg/kg levodopa

Administration of the test compositions and analysis of their activitywere as described in Example 4.

Results

The results are presented in FIGS. 3 and 4. Again, attachment of atranslucent diffuser over the left eye induced a significant myopicshift in refraction (G2, FIG. 3) associated with excessive axialelongation (G2, FIG. 4), relative to that seen in contralateral controleyes (G2, FIGS. 3 and 4; refraction, p<0.001; axial length, p<0.001) orage-matched untreated control eyes (G1, FIGS. 3 and 4; refraction,p<0.001; axial length, p<0.001). There was no difference in therefractive development or axial length between contralateral controleyes of different treatment groups relative to each other (p=0.27) orage-matched untreated eyes (p=0.21).

Daily administration of levodopa/carbidopa compositions abolished thedevelopment of FDM, such that no differences were seen in the axialelongation or refractive development in response to diffuser-wear whencompared with the contralateral control (refraction, p<0.01; axiallength, p<0.01) or age-matched untreated (refraction, p<0.01; axiallength, p<0.01) eyes (G3 and G5, FIGS. 3 and 4). Daily administration oflevodopa compositions reduced the development of FDM when compared tothe positive control (G2, FIGS. 3 and 4; refraction, p<0.05; axiallength, p<0.05). However, this inhibition was to a significantly lowerextent than compositions comprising the combination of levodopa andcarbidopa.

Example 6—Method of Producing 0.003% W/V Levodopa Composition

0.12 mg levodopa was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS (solution isapproximately pH 2). Once levodopa was dissolved, the solution wasadjusted to a pH of 6 using sodium hydroxide to obtain a final volume of4 mL.

Example 7—Method of Producing 0.03% W/V Levodopa Composition

1.2 mg levodopa was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS (solution isapproximately pH 2). Once levodopa was dissolved, the solution wasadjusted to a pH of 6 using sodium hydroxide to obtain a final volume of4 mL.

Example 8—Method of Producing 0.03% W/V Levodopa, 10% V/V DMSOComposition

1.2 mg levodopa was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid, 10% DMSO and 1×PBS. Once levodopawas dissolved, the solution was adjusted to a pH of 6 using sodiumhydroxide to obtain a final volume of 4 mL.

Example 9—Method of Producing 0.3% W/V Levodopa, 10% V/V DMSOComposition

12 mg levodopa was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid, 10% DMSO and 1×PBS. Once levodopawas dissolved, the solution was adjusted to a pH of 6 using sodiumhydroxide to obtain a final volume of 4 mL.

Example 10—Method of Producing 0.03% W/V Levodopa, 0.03% W/V2-Amino-6,7-Dihydroxy-1,2,3,4-Tetrahydronaphthalene Hydrobromide (ADTN)Composition

1.2 mg levodopa (1.5 mM) was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS. Once levodopa wasdissolved, the solution was adjusted to a pH of 6 using sodiumhydroxide, and 1.2 mg ADTN (1 mM; in the form of2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide;commercially available from Sigma Aldrich Co. LLC) was dissolved in thesolution to a final volume of 4 mL.

Example 11—Method of Producing 0.03% W/V Levodopa, 0.14% W/V AtropineComposition

1.2 mg levodopa (1.5 mM) was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS. Once levodopa wasdissolved, the solution was adjusted to a pH of 6 using sodiumhydroxide, and 5.6 mg atropine (2 mM; in the form of atropine sulfatesalt monohydrate, commercially available from Sigma Aldrich Co. LLC) wasdissolved in the solution to a final volume of 4 mL.

Example 12—Method of Producing 0.03% W/V Levodopa, 0.7% W/V PirenzepineComposition

1.2 mg levodopa (1.5 mM) was dissolved in a solution containing 0.15 Mhydrochloric acid, 0.1% ascorbic acid and 1×PBS. Once levodopa wasdissolved, the solution was adjusted to a pH of 6 using sodiumhydroxide, and 28 mg pirenzepine (16 mM; in the form of pirenzepinedihydrochloride, commercially available from Sigma Aldrich Co. LLC) wasdissolved in the solution to a final volume of 4 mL.

Example 13—Effect of Levodopa Dose and Presence of DMSO on Prevention ofForm Deprivation Myopia

120 male White Cockerel chickens were randomly assigned to one of 24treatment groups (n=5 per group) as defined below and were treated for afive day period. G1-G24 represent the labelling system used in FIGS.5-8.

G1. Age-matched untreated control groupG2. Chicks fitted with a translucent diffuser over their left eye toinduce FDMG3. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily oral administration of 20 mg/kg levodopa as apowderG4. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily oral administration of 20 mg/kg levodopa and 5mg/kg carbidopa as a powderG5. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal injection of the composition ofExample 6 (0.003% w/v levodopa)G6. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal injection of the composition ofExample 7 (0.03% w/v levodopa)G7. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal injection of the composition ofExample 1 (0.3% w/v levodopa)G8. Daily intravitreal injection of the composition of Example 1 (0.3%w/v levodopa)G9. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal injection of the composition ofExample 3 (0.03% w/v levodopa, 0.008% w/v carbidopa)G10. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal injection of the composition ofExample 2 (0.3% w/v levodopa, 0.08% w/v carbidopa)G11. Daily intravitreal injection of the composition of Example 2 (0.3%w/v levodopa, 0.08% w/v carbidopa)G12. Age-matched untreated control groupG13. Chicks fitted with a translucent diffuser over their left eye toinduce FDMG14. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily oral administration of 20 mg/kg levodopa as apowderG15. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily oral administration of 20 mg/kg levodopa and 5mg/kg carbidopa as a powderG16. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 6 (0.003% w/v levodopa)G17. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 7 (0.03% w/v levodopa)G18. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 1 (0.3% w/v levodopa)G19. Daily topical administration of the composition of Example 1 (0.3%w/v levodopa)G20. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 3 (0.03% w/v levodopa, 0.008% w/v carbidopa)G21. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 2 (0.3% w/v levodopa, 0.08% w/v carbidopa)G22. Daily topical administration of the composition of Example 2 (0.3%w/v levodopa, 0.08% w/v carbidopa)G23. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 8 (0.03% w/v levodopa, 10% DMSO)G24. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 9 (0.3% w/v levodopa, 10% DMSO)

Administration of the test compositions and analysis of their activitywere as described in Example 4.

Results

The results are presented in FIGS. 5 to 8. Attachment of a translucentdiffuser over the left eye induced a significant myopic shift inrefraction (G2, FIG. 5; and G13, FIG. 7; p<0.001) associated withexcessive axial elongation (G2, FIG. 6; and G13, FIG. 8; p<0.001)relative to that seen in the age-matched untreated control eyes (G1,FIGS. 5 and 6; and G12, FIGS. 7 and 8).

Daily intravitreal injection of levodopa compositions significantlyinhibited the development of FDM, with administration of a 0.3% w/vlevodopa composition having the greatest effect (G5, p<0.01; G6, p<0.01;and G7, p<0.001; FIG. 5; and G5, p<0.01; G6, p<0.001; G7, p<0.001; FIG.6). This effect was significantly greater than oral administration oflevodopa (G3, FIGS. 5 and 6). Addition of the aromatic L-amino aciddecarboxylase inhibitor, carbidopa, increased the inhibitory effect ofthe compositions (G9, p<0.01; and G10, p<0.01; FIG. 5; and G9, p<0.001;and G10, p<0.001; FIG. 6) in comparison with compositions comprisinglevodopa alone.

Daily topical administration of levodopa compositions significantlyinhibited the development of FDM (G16, p<0.05; G17, p<0.01; and G18,p<0.01; FIG. 7; and G16, p<0.01; G17, p<0.01; and G18, p<0.01; FIG. 8)and demonstrated a stronger effect than oral levodopa administration(G14, FIGS. 7 and 8). Again, the addition of carbidopa to thecompositions significantly increased the inhibitory effect (G20, p<0.01;and G21, p<0.01 FIG. 7; and G20, p<0.001; and G21, p<0.001; FIG. 8) incomparison with compositions comprising levodopa alone.

The addition of 10% DMSO to the topical levodopa compositionssignificantly increased the inhibitory effect against the development ofFDM (G23, p<0.01; and G24, p<0.01; FIG. 7; and G23, p<0.001; and G24,p<0.001; FIG. 8) relative to the corresponding compositions comprisinglevodopa alone.

Example 14—Safety and Efficacy of Topical Levodopa Administration Over aFour Week Period

To evaluate the safety and effectiveness of topical treatment oflevodopa, twice daily eye-drop administration of a 15 mM (0.3% w/v)levodopa composition (prepared in accordance with Example 1) was testedover a period of four weeks. Male White Cockerel chickens were keptunder normal laboratory light (500 lux, fluorescent lights) on a 12:12hour light:dark cycle with lights on at 9:30 am and off at 9:30 pm. Inall chicks, left eyes were treated experimentally while right eyesremained untreated to serve as a contralateral control. Chicks wererandomly assigned to one of four groups (n=6 for each group) and treatedover the four week period under the following experimental conditions:

-   -   1. Age-matched untreated controls: Chicks remained untreated,        receiving no ocular or levodopa treatment    -   2. Form-deprivation myopia (FDM): Chicks were fitted with a        translucent diffuser over their left eye to induce FDM,        receiving no further treatment    -   3. Form-deprivation myopia and topical 0.3% w/v (15 mM) levodopa        treatment: Chicks were fitted with a translucent diffuser over        their left eye to induce FDM and were administered the        composition of Example 1 topically twice daily (9:30 am and 2        pm)    -   4. Topical 0.3% w/v (15 mM) levodopa treatment to otherwise        untreated eyes: Chicks were administered the composition of        Example 1 topically twice daily (9:30 am and 2 pm)

Administration of the test compositions was performed in accordance withthat described in Example 4.

To determine changes in the rate of eye growth and the development ofmyopia, axial length and refraction were measured using A-scanultrasonography (Biometer AL-100; Tomey Corporation, Nagoya, Japan) andautomated infrared photo-retinoscopy, respectively. Ocular measurements(axial length and refraction) were made on day one (prior to thecommencement of experimentation) and every seven days for four weeks.

Results

The results are presented in FIGS. 9 and 10. A multivariate analysis ofvariance (MANOVA) with repeated measures design was used to compare theeffect of the different treatment regimens over time. Animals fittedwith translucent diffusers and treated with topical levodopa saw asignificantly smaller myopic shift in refraction in comparison to thoseanimals fitted with translucent diffusers in the absence of levodopatreatment (FIG. 9; F(3,21)=191.013; p<0.001). Furthermore, animalsfitted with translucent diffusers and treated with topical levodopashowed decreased axial elongation in comparison to those animals fittedwith translucent diffusers in the absence of levodopa treatment (FIG.10; (F3,21)=34.129; p<0.001).

Example 15—Effect of Co-Treatment of Levodopa with ADTN, Atropine andPirenzepine on Form Deprivation Myopia Development

70 male White Cockerel chickens were randomly assigned to one of 14treatment groups as defined below (n=5 per group) and were treated for afive day period. G1-G14 represent the labelling system used in FIGS. 11and 12.

G1. Age-matched untreated control groupG2. Chicks fitted with a translucent diffuser over their left eye toinduce FDMG3. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal injection of a composition containing1 mM ADTN (0.03% w/v) and 0.1% ascorbic acid in 1×PBS (pH 7)G4. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of a composition containing1 mM ADTN (0.03% w/v) and 0.1% ascorbic acid in 1×PBS (pH 7)G5, G9 and G13. Chicks fitted with a translucent diffuser over theirleft eye to induce FDM and daily topical administration of thecomposition of Example 7 (0.03% w/v levodopa)G6. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 10 (0.03% w/v levodopa, 0.03% w/v ADTN)G7. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal administration of a compositioncontaining 2 mM atropine (0.14% w/v; in the form of atropine sulfatesalt monohydrate) in distilled water (pH 7)G8. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of a composition containing2 mM atropine (0.14% w/v; in the form of atropine sulfate saltmonohydrate) in distilled water (pH 7)G10. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 11 (0.03% w/v levodopa, 0.14% w/v atropine)G11. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily intravitreal administration of a compositioncontaining 16 mM pirenzepine (0.7% w/v; in the form of pirenzepinedihydrochloride) in distilled water (pH 7)G12. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of a composition containing16 mM pirenzepine (0.7% w/v; in the form of pirenzepine dihydrochloride)in distilled water (pH 7)G14. Chicks fitted with a translucent diffuser over their left eye toinduce FDM and daily topical administration of the composition ofExample 12 (0.03% w/v levodopa, 0.7% w/v pirenzepine)

ADTN compositions were prepared by dissolving ADTN in a solutioncontaining 0.1% ascorbic acid in 1×PBS to a final concentration of 1 mM(0.03% w/v), and adjusting the pH to 7. Atropine and pirenzepinecompositions were prepared by dissolving atropine (in the form ofatropine sulfate salt monohydrate) or pirenzepine (in the form ofpirenzepine dihydrochloride) in distilled water to a final concentrationof 2 mM (0.14% w/v) and 16 mM (0.7% w/v), respectively, and adjustingthe pH to 7.

Administration of test compositions and measurement of ocular parameterswas performed in accordance with that described in Example 4.

Results

The results are presented in FIGS. 11 and 12. Daily administration ofthe dopamine D2 receptor agonist, ADTN (G3 and G4), significantlyinhibited the myopic shift in refraction and decreased axial elongationin comparison with animals fitted with a translucent diffuser only (G2),with intravitreal injection having a greater effect than topicaladministration (G3, p<0.01; and G4, p<0.05; FIG. 11; G3, p<0.001; andG4, p<0.05; FIG. 12). Notably, topical administration of a compositioncomprising both ADTN and levodopa inhibited the myopic shift inrefraction (G6, p<0.01; FIG. 11) and decreased axial elongation (G6,p<0.01; FIG. 12) to a greater extent than either compound alone (G4 andG5, respectively; FIGS. 11 and 12).

Daily administration of the muscarinic acetylcholine receptorantagonist, atropine (G7 and G8, FIGS. 11 and 12), significantlyinhibited the myopic shift in refraction and decreased axial elongationin comparison with animals fitted with a translucent diffuser only (G2),with intravitreal injection having a greater effect than topicaladministration (G7, p<0.01; and G8, p<0.05; FIG. 11; G7, p<0.001; andG8, p<0.05; FIG. 12). Topical administration of a composition comprisingboth atropine and levodopa inhibited the myopic shift in refraction(G10, p<0.01; FIG. 11) and decreased axial elongation (G10, p<0.01; FIG.12) to a greater extent than either compound alone (G8 and G9,respectively; FIGS. 11 and 12).

The M1 muscarinic acetylcholine receptor antagonist, pirenzepine (G11and G12, FIGS. 11 and 12), significantly inhibited myopic shifts inrefractive development and decreased axial elongation in comparison withanimals fitted with a translucent diffuser only (G11, p<0.01; and G12,p<0.05; FIG. 11; G11, p<0.001; and G12, p<0.05; FIG. 12). The effects ofpirenzepine were greater when intravitreally administered (G11, FIGS. 11and 12). Topical administration of the combination of pirenzepine andlevodopa (G14, FIGS. 11 and 12) had a greater inhibitory effect thantopical administration of either compound alone on refractivedevelopment (G14, p<0.01; FIG. 11) and axial length (G14, p<0.01; FIG.12).

Example 16—Histological Analysis of Effects of Topical LevodopaAdministration on Form Deprivation Myopia Development

For base histological analysis using toluidine blue staining,paraformaldehyde fixed retinal sections were immersed in an aqueous 1%toluidine blue (Sigma Aldrich, Catalogue No. 89640) solution for 1.5minutes prior to rinsing under running distilled water for 2 minutes.Sections were then mounted in glycerol before cover slipping. Sectionswere viewed on a Motic BA410 light microscope at 40× magnification andcaptured by a Moticam 10.0 megapixel camera in conjunction with theMotic Live Imaging Module.

Retinal sections were from eyes of male White Cockerel chickens asfollows:

-   -   A. Contralateral control eye of chick, wherein the other eye is        fitted with a translucent diffuser to induce FDM    -   B. Eye of chick fitted with a translucent diffuser to induce FDM    -   C. Contralateral control eye of chick, wherein the other eye is        fitted with a translucent diffuser to induce FDM and is treated        with daily topical administration of the composition of Example        1 (0.3% w/v levodopa)    -   D. Eye of chick fitted with a translucent diffuser to induce FDM        and treated with daily topical administration of the composition        of Example 1 (0.3% w/v levodopa)    -   E. Contralateral control eye of chick, wherein the other eye is        treated with daily topical administration of the composition of        Example 1 (0.3% w/v levodopa)    -   F. Eye of chick treated with daily topical administration of the        composition of Example 1 (0.3% w/v levodopa)    -   G. Eye of age-matched untreated control chick

Administration of levodopa compositions was performed in accordance withthat described in Example 4.

Results

The results are presented in FIG. 13. As can be seen in FIG. 13, noalteration in retinal architecture or cell density was seen in the eyesof the following groups: age-matched untreated control (FIG. 13G),form-deprived (FIG. 13B), contralateral untreated control eyes of allconditions (FIGS. 13A, 13C and 13E), form-deprived and daily topicaladministration of a composition comprising 0.3% w/v levodopa (FIG. 13D),and daily topical administration of a composition comprising 0.3% w/vlevodopa into otherwise untreated animals (FIG. 13F). Thus, the levodopacompositions do not display retinal toxicity.

Example 17—TUNEL Staining Analysis of Effects of Topical LevodopaAdministration on Form Deprivation Myopia Development

TUNEL staining was undertaken using the Roche In Situ Cell DeathDetection Kit, AP (Sigma Aldrich, Catalogue No. 11684795910). Theprotocol used for staining retinal sections from male White Cockerelchickens was adapted from the work of Denton and Kumar (2015) ColdSpring Harb Protoc; doi:10.1101/pdb.prot086199. In short, retinalsections were prepared by washing in three changes of 1×PBS in 0.1%Triton X-100 (1×PBST), permeabilizing in 0.1% sodium citrate on ice forfive minutes, followed by washing in three more changes of 1×PBST.Sections were then incubated in TUNEL Reaction Mixture according to themanufacturer's instructions (negative controls were incubated inLabelling Mixture only, whilst positive controls were incubated in DNase1 (100 U/mL) for 10 minutes prior to TUNEL labelling to induce DNAfragmentation like that observed in apoptosis). Following TUNELlabelling, sections were washed in the dark in three changes of 1×PBS,followed by visualization using a Leica DMIL fluorescent microscope at20× magnification with images captured by a Leica DFC425 camera usingthe Leica Application Suite version 4.8.

Analysed samples were as follows:

-   -   A. Negative control (retinal section treated with labelling        solution only)    -   B. Positive control (retinal section treated with DNase 1 to        induce DNA strand breakage, which is indicative of apoptosis)    -   C. Retinal section from eye of age-matched untreated control        chick    -   D. Retinal section from eye of chick fitted with a translucent        diffuser to induce FDM    -   E. Retinal section from eye of chick treated with daily topical        administration of the composition of Example 1 (0.3% w/v        levodopa)    -   F. Retinal section from eye of chick fitted with a translucent        diffuser to induce FDM and treated with daily topical        administration of the composition of Example 1 (0.3% w/v        levodopa)

Administration of levodopa compositions was performed in accordance withthat described in Example 4.

Results

As can be seen in FIG. 14, retinal cells do not show signs of apoptosisin response to form-deprivation (FIG. 14D) or levodopa treatment (FIGS.14E and 14F) when compared to positive control retinal tissue treatedwith DNase 1 to induce DNA nicks and genomic degradation (FIG. 14B). Dueto no staining being present, visualization required over exposure ofall but the positive control retinal sections, leading to the lighterappearance observed.

The disclosure of every patent, patent application, and publicationcited herein is hereby incorporated herein by reference in its entirety.

The citation of any reference herein should not be construed as anadmission that such reference is available as “Prior Art” to the instantapplication.

Throughout the specification the aim has been to describe the preferredembodiments of the invention without limiting the invention to any oneembodiment or specific collection of features. Those of skill in the artwill therefore appreciate that, in light of the instant disclosure,various modifications and changes can be made in the particularembodiments exemplified without departing from the scope of the presentinvention. All such modifications and changes are intended to beincluded within the scope of the appended claims.

What is claimed is:
 1. A pharmaceutical ocular composition, comprising,levodopa, an antioxidant and an aqueous carrier.
 2. The compositionaccording to claim 1, wherein the antioxidant is selected from the groupconsisting of ascorbic acid, phenolic acids, sorbic acid, sodiumbisulfite, sodium metabisulfite, acetyl cysteine, sodium thiosulfate,ethylene diamine tetraacetic acid, sodium nitrite, ascorbyl stearate,ascorbyl palmitate, alpha-thioglycerol, erythorbic acid, cysteinehydrochloride, citric acid, tocopherol or vitamin E, tocopherol acetate,dibutylhydroxytoluene, soybean lecithin, sodium thioglycolate,butylhydroxyanisole, propyl gallate, uric acid, melatonin, thiourea, andsalts and combinations thereof.
 3. The composition according to claim 2,wherein the antioxidant is ascorbic acid.
 4. The composition accordingto claim 1, further comprising an inhibitor of aromatic L-amino aciddecarboxylase.
 5. The composition according to claim 4, wherein theinhibitor of aromatic L-amino acid decarboxylase is selected fromcarbidopa, benserazide, methyldopa and combinations thereof.
 6. Thecomposition according to claim 5, wherein the inhibitor of aromaticL-amino acid decarboxylase is carbidopa.
 7. The composition according toclaim 4, wherein the ratio of levodopa to the inhibitor of aromaticL-amino acid decarboxylase is in the range of from 20:1 to 1:1.
 8. Thecomposition according to claim 1, wherein the composition furthercomprises a dopamine receptor agonist.
 9. The composition according toclaim 8, wherein the dopamine receptor agonist is selected from thegroup consisting of quinpirole, apomorphine, ropinirole, pramipexole,dexpramipexole, piribedil, rotigotine, bromocriptine, lisuride,cabergoline, 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene,pergolide, calidopa, dihydrexidine, doxathrine, propylnorapomorphine,quinagolide, roxindole, sumanirole, fenoldopam, ergocornine,1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol,2-(N-phenethyl-N-propyl)amino-5-hydroxytetralin, dihydroergotamine,(1R,3S)-1-(aminomethyl)-3-phenyl-3,4-dihydro-1H-isochromene-5,6-diol,carmoxirole, fenoldopam, and salts and combinations thereof.
 10. Thecomposition according to claim 1, wherein the composition furthercomprises a GABA receptor antagonist.
 11. The composition according toclaim 10, wherein the GABA receptor antagonist is selected from thegroup consisting of bicuculline, flumazenil, gabazine,phenylenetetrazol, (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinicacid, (3-aminopropyl)(cyclohexylmethyl)phosphinic acid, and salts andcombinations thereof.
 12. The composition according to claim 1, whereinthe composition further comprises a muscarinic acetylcholine receptorantagonist.
 13. The composition according to claim 12, wherein themuscarinic acetylcholine receptor antagonist is selected from the groupconsisting of atropine, pirenzepine, himbacine, hyoscine,cyclopentolate, ipratropium, oxitropium, tropicamide, oxybutynin,tolterodine, diphenhydramine, dicycloverine, flavoxate, tiotropium,trihexyphenidyl, solifenacin, darifenacin, benzatropine, mebeverine,procyclidine, aclidinium, and salts and combinations thereof.
 14. Thecomposition according to claim 1, wherein the aqueous carrier isselected from the group consisting of saline, water, aqueous buffer, anaqueous solution comprising water and a miscible solvent, andcombinations thereof.
 15. The composition according to claim 1, whereinthe pH of the composition is in the range of from 5.5 to
 6. 16. Thecomposition according to claim 1, wherein the composition is formulatedfor topical administration to the eye.
 17. A method of inhibiting theprogression or development of a visual disorder in a subject, comprisingadministering to the subject the composition according to claim
 1. 18.The method according to claim 17, wherein the visual disorder isselected from the group consisting of a visual disorder associated withdiabetic retinopathy, and myopia.
 19. The method according to claim 18,wherein the visual disorder is myopia.
 20. A process for preparing thecomposition according to claim 1, comprising dissolving levodopa in theaqueous carrier at a pH in the range of from 0.5 to 2.5, adding theantioxidant to the composition and adjusting the pH of the compositionto a pH in the range of from 5 to 8.